When there are only two cells at the beginning, the competition between proliferation and migration may be very remarkable. When a cancer cell is undergoing division, does it slow down/stop migration?
To divide, a cell needs to round up, meaning that it becomes a kind of bubble. It stops migrating because this bubble grows up, not stretches to sides. In that sense no, they are not migrating when dividing, unless you can consider upward movement a "migration" movement.